There are two main types of vehicle navigation systems currently in use.
The first type of system includes a navigation-capable device, e.g. a GPS-based device, located in a vehicle which performs all required computations and contains all necessary navigation data. In this system, the navigation functions are restricted to the vehicle and can be performed anywhere in an area covered by navigation data stored in the device. A device according to this type of system requires a large amount of computational power, memory, and a large amount of map data storage.
Disadvantageously, there is no way to easily update frequently changing information, i.e. transitory information, stored in the system, e.g. restaurant names, traffic conditions/road conditions, construction projects, etc. Current in-vehicle navigation systems allow traffic information update using radio link information about traffic conditions at predetermined locations. Disadvantageously, this time critical information is not reconfigurable on-the-fly, the traffic information is only available for the predetermined points at the time of map creation. If the transitive information is stored in the system, data stored in data storage on the system requires complete replacement or update of the data. If only a small portion of the data changes or if the changes are frequent in nature, the replace/update process becomes tedious to a user. Further, if the user fails to update just prior to leaving for a destination and traffic conditions change, the user may be frustrated to encounter significant traffic delays.
The second type of system includes data and computational power hosted remote from the device. Smaller local maps and routing directions are then provided to the device over a network connection, e.g. a cellular telephone network, a system employing this type of architecture requires a powerful central server to perform route computation and a central database collocated with the server for storing map data. Disadvantageously, navigation capability, e.g. GPS, is required at the user device which further must be able to perform map matching or route following to display turn instructions at the correct time. Under this system, the primary objective is to move the additional cost and complexity required to perform navigation and store map data from a user device, e.g. a personal digital assistant (PDA) or a cellular telephone, to a central server. This trade-off allows for a simpler user device; however, transmission of server generated maps and routing increases the cost and bandwidth required.
Several additional disadvantages of such an approach include:
The cellular phone still requires the additional cost of a GPS or other navigational capability and must be capable of performing maps matching and route following computations;
Network capabilities and communication bandwidth can become swamped or overwhelmed if a large number of users require routing services at the same time, e.g. multiple requests from users for rerouting during rush-hour traffic; and
The cellular phone must be in constant contact with the server in order to receive updated directions and information.
Based on the foregoing discussion, there is a need in the art for a third type of system able to perform complex computations, e.g. maps matching and route following, and store large amounts of maps data without being tied to a specific installation location and able to receive updates and other navigation information without requiring constant connection time and high bandwidth.